Product and process of preparing same



Patented July 5,1938

UNITED. STATES PATENT OFFICE PRODUCT AND PROCESS OF PREPARING SAMEErnest K. Gladding, Buffalo, N. Y., and Dorothy Bateman Maney, OldHickory, Tenn., assignors, by mesne assignments, to E. I. du Pont deNemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application June 17, 1936,

Serial No. 85,768

V 22 Claims.

ucts containing large amounts of water or mis-;

ture. The invention also pertains to methods for producing such coatedsheets or films. This application is a continuation in part of theapplication of Ernest K. Gladding and Dorothy E. Bateman, Ser. No.731,603, filed June 21, 1934 for Product and process of preparing same.

Ordinary sheets or films of regenerated cellulose have been renderedmoistureproof by coating with a moistureproofing composition comprisingin its preferred form a fiowable solution of a cellulose derivative, awax or wax-like material, a blending agent and a plasticizer. Thesecoated sheets or films are very effective as a wrapping material forsuch products as bread, cake, candy,

or the like which it is desired to maintain in substantially theiroriginal fresh condition'without any'change in moisture content. Suchcoated sheets or films, when used as a wrapping material which isdirectly held in contact with products having an exceedingly high wateror moisture content, such as butter, cheese, wet or frozen fish, icecream or the like, and when such articles are kept over long periods oftime in storage, have the disadvantage that the moistureproof coatingtends to loosen and/or flake off from the sheet of regenerated celluloseand to thereby lessen the moistureproof quality of the wrappingmaterial. It is an object of this invention to provide a flexible,substantially odorless, non-fibrous cellulosic'sheet or film having asurface coating which will adhere tenaciously to the cellulosic sheet orfilm. A further object comprises the production of films of thischaracter having a moistureproofing coating comprising a cellulosederivative, a wax or wax-like material, a blending agent and aplasticizer. A still further object of th'e'invention comprises asimple, workable process, directly applicable to existing equipment,such as is used for the manufacture of regenerated cellulose sheets orfilms, for producing products having the'characteristics described Afurther object of the invention resides in the production oftransparent, flexible, non-fibrous, cellulosic sheets or films preparedby precipitation from an aqueous cellulosic dispersion, coated 55 and/orsized. with an amino polymer, and having a moistureproof surface coatingwhich remains firmly. anchored to the cellulosic sheet or film even whenin direct contact with water over long periods of time.

A specific object of the invention resides in the 5 production oftransparent, flexible, substantially odorless, non-fibrous cellulosicsheets or films prepared by precipitation from an aqueous cellulosicdispersion, coated and/or sized with a de-acetylated chitin, and havinga moistureproof sur- 10 face coating which remains firmly anchored tothe cellulosic sheet or film even when in direct contact with Water ormoisture over a prolonged period of time.

Other objects of the invention will appear from 15 the followingdescription.

These objects are accomplished by the following invention which, in itspreferred form, contemplates forming a cellulosic sheet or film,applying to said sheet or film a surface coating having moistureproofingcharacteristics and applying directly to the cellulosic base andintermediate said base and the surface coating, a coating and/or sizingof an amino polymer and preferably of a de-acetylated chitin. 25

The following examples illustrate modes of applying the principles ofthe invention.

Example I i A sheet of regenerated cellulose in the gel state.; 30 whichhas been cast from viscose, desulfured, bleached, and washed free fromimpurities in the usual manner on the casting machine and is ready forthe glycerin treatment, is led through an aqueous glycerin bath, which,in addition to- 5 4 per cent by weight of glycerin, also contains oneper cent by weight of a de-acetylated chitin, and-0.28 per cent byweight of acetic acid (calculated as 100 per cent acetic acid).

Acetic acid is used in order to render thedeacetylated chitin soluble.In this example, the acetic acid used corresponds to 75 per cent of theamount of acid theoretically required to completely react with thede-acetylated chitin used when a ratio of 161 to 60 is employed toexpress the relation of de-acetylated chitin to acetic acid in terms ofmolecular weights.

The sheet of regenerated cellulose is held in contact with the aqueoussolution of the salt of de-acetylated chitin and glycerin for from 10 to20 seconds after which the excess solution is removed from the sheet bymeans of squeeze rolls which reduce the water content of the sheet tobetween three and four times the weight of the cellulose, after whichthe sheet of regenerated whichhas been treated with the aqueous glycerinsolution containing .the size (the de-acetylated chitin) may be carriedout according to the usual method for drying regenerated cellulosesheeting on the casting machine by bringing the sheet directly from thesqueeze rolls into contact with heated rolls which dry the sheet attemperatures preferably between 50 and 90 degrees centigrade. However,there may be a tendency for the size to be deposited on the dryer rollswhen they become wet with the solubilized de-acetylated chitin from thewet fihn passing over them. This deposit, resulting from the heat actingon the soluble size, may flake off from time to time on the fresh filmpassing over the dryer rolls, thereby imparting a faintly mottledappearance to the finished film.

Therefore, in this preferred example, the regenerated cellulose sheet,wet with a solution of glycerin and the size, after passing through thesqueeze rolls and beforecomingi into contact with the dryer rolls, isfirst given a preliminary partial drying out of contact with any surfaceby passing the sheet through air heated to an elevated temperature bymeans of any suitable arrangement, whereby the moisture content of thesheet is reduced to any desired extent, for instance, from one-tenth toone-half of its initial water content before coming in contact with thedryer rolls of the casting machine to complete the drying operation inthe usual manner.

The resulting sheet of regenerated cellulose coated or sized with aninsoluble deposit of deacetylated chitin may be conditioned if necessaryto bring it to the desired moisture content and is then coated with amoistureproofing composition of the following formula:

Parts by weight Py y Gum damar 4.64 Dibutyl phthalate 2.80 Paramn, M.P.-61 C 0.48 Zinc stearate 0,15 Ethyl acetate 56.34 Toluene 28.53 Alcohol3.20 Acetone 0.11

The sheet is passed through the moistureproofing composition, the excessof which is removed by desired moisture content. The resulting productis a sheet of regenerated cellulose with a moistureproofin'g coating,which is substantially odorless, transparent, flexible, andmoistureproof,

' and to which, by virtue'of the sheet being coated or sized with ade-acetylated chitin, the moistureproof coating adheres or is anchoredvery tenaciously when the sheet is in direct contact with water or isused as a wrapping directly in contact with products containing largeamounts of water or moisture such as butter, cheese, wet

e ails or frozen fish, ice cream, or the like, for very substantialperiods of time, for example, for a month or more.

Example I! A sheet of regenerated cellulose in the gel state is passedthrough an aqueous bath containing 4 per cent by weight of glycerin, 0.7per cent by weight of a de-acetylated chitin, and 0.2 per cent by weightof formic acid, or any other amount of formic acid sufiicient to renderthe size water-soluble.

In this example, the amount of formic acid used is 80% of thattheoretically required to completely react with the de-aeetylated chitinto form the desired formate, assuming the molecular ratio ofde-acetylated chitin to formic acid to be 161 to 46.

After being held in contact with this bath for 10 to 20 seconds, thecellulosic sheet is freed from excess solution by means of squeeze rollsso that the water content of the sheet is between three and four timesthe weight of the cellulose and the sheet is then dried either by beingled directly over heatedrolls, or as in Example I, by means of apreliminary partial drying in hot air out of contact with any surface,followed by passage over dryer rolls to complete the drying. In eithercase the drying of the sheet may be accompanied by a treatment withgaseous ammonia which facilitates the conversirn of the water-solubleformate salt of the de-a'cetylated chitin to an insoluble product.

A moistureproofing coating is applied to the sheet of regeneratedcellulose treated as described above in this example by passing thesheet through a bath comprising ethyl cellulose, a wax, a blending agentand a plasticizer, re-

moving the excess moistureproofing bath and removing the solvent at atemperature above the melting point of the wax, after which the coated,

ties which have been'described for the moistureproof film produced inple I. 1

" Example III A finished or dry sheet of glycol cellulose is accordancewith Exampassed through an aqueous solution containing 0.5% by weight ofde-acetylated chitin which has been converted to the acetate by aceticacid in an amount which is 0.15% by weight of the 1 aqueous solution(calculated on the basis of acetic acid). After removing the excesssolution from the sheet in any suitable manner, the sheet is dried at 80degrees centigrade and subsequently coated with a moistureproofiingcomposition comprising a solution of nitrocellulose, gum darnar,paraffin and dibutyl phthalate. The excess moistureproofing material andthe solvent may be removed as described in the preceding example.

Example IV The diethylaminoethyl methacrylate polymer produced inaccordance with the procedure outlined in Example B (below) is dissolvedin dilute acetic acid containing 5-6% glycerol to form a solutioncontaining 0.25-1.00% of the resinous polymer, sufiicient acetic acidbeing used to just solubilize the polymer. Sheets of gelregeneratedcellulose film 'are immersed in this solution and allowed toremain'five'minutes, whereupon they are removed and the excess solutiondrained oil. The sheets are thendried in an oven at C.

Sufilcient beta-amino ethoxyethyl cellulose to form a 2% solution isdissolved in an aqueous mixture containing 1.5% acetic acid andglycerol. Sheets of gel regenerated cellulose film freed-from excesswater are immersed in this solution at room temperature for 5 minutes,after which they are removed and allowed to drain, the excess of therather viscous solution being scraped oil? by means of glass rods. Thetreated film is then placed on a drying frame and dried in an oven at120 C. for minutes. The dry film is then coated with a moistureproofinglacquer in the usual manner to produce a clear,

"transparent, flexible and moistureproof product.

agent.

The anchorage of the moistureproofing coating is equal to or better thanthat obtained through the use of deacetylated chitin as the anchoringExample VI An aqueous solution containing 2% of diethylamino methyl zeinis prepared by dissolving the amino polymer in dilute acetic acidcontaining 0.28 partsof acetic acid for each part of the zein derivativeand 56% glycerol. Films of gel regenerated-cellulose are treated as inthe preceding examples. the drying time being 30 minutes at 120 C. Theanchorage obtained after moistureproofing is somewhat inferior to thatobtained through the use of de-acetylated chitin alone. The use of a 1%solution of the zein derivative results in some improvement in theanchorage and the use of a combination of 1% solution of the zeinderivative and 1% solution of deacetylated chitin produces anchorageresults which are better than those obtained with either whe used alonein 2% concentration,

Example VII An aqueous solution containing 2% plperidyl methyl zein isprepared by dissolving in water containing 0.28 part of acetic acid perpart of above and coated with a moistureproofing composition shows animproved anchorage which, thoughinferior to that of de-acetylated chitinis quite satisfactory.

Eaiample VIII 'A 2%- solution of the phenol-formaldehydedimethylamineresin (Example E below) is prepared by dissolving the resin in anaqueous solutlon containing 1.5% acetic acid and 6% glycerin and thissolution was used as a treating bath for regenerated cellulose film. Thetreated film is dried for 30 minutes at 120 C. and the moistureproofproduct shows anchorage approximately equal to that of de-acetylatedchitin with some improvement over the latter when the anchorage testswere made in water containing 0.1% acetic acid.

Example IX Q A meta-creso1-dimethylamine-formaldehyde resin similar tothe resin described in Example E (below) is dissolved in dilute aceticacid con-'- final material taining 5-6% glycerol to form a solutioncontaining 2% of the resin. When used as the anchoring agent, as in thepreceding examples, the results obtained are comparable to thoseobtained with deacetylated chitin. A 1% solution of the Example X Adicyclohexyl amino ethyl methacrylate prepared in a manner similar tothat described in Example B (below) may be used in either its monomericor polymeric forms. Mixtures of the monomer and polymer have been-foundto be particularly useful, the resinous material being brought intosolution by means of dilute acetic acid. A 2% solution is capable ofproducing a which will show an anchorage approximately equal to that ofthe de-acetylated chitin. The anchorage can be improved somewhat byusing as the anchoring agent a combination of these monomers and/0rpolymers with de-acetylated chitin.

This invention contemplates, as a base, any smooth, dense, non-porous,non-fibrous cellulosic sheet or film which may be precipitated from anaqueous cellulosic dispersion. Thus, the scope of the invention includesthe use of sheets or films of regenerated cellulose, whetherprecipitated from solutions of viscose, cuprammonium cellulose, or anyother aqueous solution or dispersion of cellulose, and it alsocontemplates the use of sheets or films of such cellulose esters andethers as are precipitated from aqueous solutions or dispersions, suchas glycol cellulose, cellulose glycolic acid, methyl cellulose and ethylcellulose of low alkyl content, cellulose phthalate, and

other cellulose products similar to those described. When any givencoating composition is applied to such cellulosic sheets or films, thecoating composition will not penetrate therethrough and will normallyresult in a surface coating. It is desired to emphasize the fact thatthe preferred form of the invention is directed to the treatment ofregenerated cellulose sheets or films since it is in this form that theinvention may be applied with the greatest advantages.v

As a surface coating, the invention contemplates the use oi any coatingcomposition containing a cellulose derivative base, such as cellulosenitrate, cellulose acetate, ethyl cellulose, benzyl cellulose or thelike, which may be. modified as desired by the addition of blendingagents, waxes, plasticizers, et cetera. In its preferred form, thisinvention contemplates as a surface coating a moistureproofing coatingcomprising a cellulose derivative, a wax or wax-like material or othermoistureproofing agent, a blending agent and a plasticizer. .Suchmoistureproofing compositions are disclosed in Charch and Prindle U. S.Patent No. 1,737,187, issued November 26, 1929.

The invention also contemplates the anchoring to. a cellulosic base ofmoistureproofing coatings which may not contain cellulosic material, e.g.. rubber-wax or resin-wax coatings, and includes also the anchoring ofcoatlngswhich may conceivably be used for purposes other than mois-'acetic 'acid. The amino nitrogen maybe primary, secondary or tertiary,part of an open chain or of a cyclic molecular structure.

The amino polymers which may. be used a anchoring agents, as illustratedin the above examples, may be subdivided into several groups as follows:

1. The first group, closely related to though nevertheless distinct fromcellulose, may be considered as hexose amine polymers, or more broadlyas carbohydrate amine polymers, which have, where necessary, beenpurified and converted into the acid soluble type. With or without suchtreatments, the highly polymeric molecule is built up by nature, and theamine nitrogen, as'a rule, is present in the natural product. Those inwhich the nitrogen is present in the substance as it exists naturallymay be of marine or insect origin on the one hand, or vegetable originon the other. De-acetylated chitin, which is by far the best example ofa nexose amine'polymer is; for example, of marine origin, and thepolymers obtained from fungi such as aspergillus niger are of vegetableorigin. .Examples of carbohydrate amine polymers in-which the highlypolymerie molecule has been built up by nature, but int-o which theamine nitrogen has been introduced syntheticallyare the alkylamin-ocelluloses. Regardless of the source of the nitrogen, this first groupalso includes various reaction products and chemical derivatives ofcarbohydrate amine polymers, provided of course that they have therequired solubility characteristics. 7

2. The second group of amino polymers coinprises that group of syntheticresins, in the making of which ammonia in someinstances and monomericamino nitrogen containing bodiesin others have beenemployed. Thisgroupisdistinct in that the highly polymeric molecules are built up wholly byartificial means, i. e.,.they are not synthesized by nature. The resinsof this group may be considered broadly as those which contain aminonitrogen and have the requisite solubility characteristics. Thefollowing types oi resins are illustrative of the classes among whichhighly polymeric amino nitrogen containing bodies falling' in thisclassification may be found. (a) Resinous polymeric amino alcohol estersof acrylic acid and of its homologues substituted in the alpha positionbya hydrocarbon radical, and (b) resinous reaction products of phenols,aldehydes and ammonia or primary or secondary amines.

(a) Examples of' the first of the above sub-- classes of resins arebeta-diethylaminoethyl alpha-methacrylate, beta piperidyl N ethylalphamethacrylate, and beta dicyclohexyl aminoethyl alpha-methacrylate' Theseresins may be prepared by spontaneous polymerization of the monomericcompounds, but for the purposes of the present invention, advantage canbe taken of a unique property of the monomers, namely their ability toform polymerizable salts with aqueous acids. The monomer as prepared maysimply be dissolved in the stcichiometrical amount or more of aqueousacid and the solution heated with a polymerization catalyst such asbenzoyl peroxide until polymerization of thesalt is effected.

(b) An example of the second of the above subclasses of resins havingamino nitrogen and the specified'soluisilities is the reaction productof meta-cresol, formaldehyde and dimethylamine. Other phenols sueh asphenol itself or p-tertiary amyl phenol may be substituted for thecresol, and the ammonia or various primary or secondary amines for thedimethylamine. It is desirable in most cases, possible in all caseaandnecessary in some cases, to react the amineor ammonia with a part of theformaldehyde before adding the remainder. These resins are to be sharplydistinguished from the phenol-aldehyde resins prepared in the presenceof only catalytic amounts of ammonia or amines, which resins cannot beemployed in accordance with the methods of this invention because theylack the pre ponderance oi amino nitrogen which induces the propersolubility characteristics. The' molal ratio of amine to phenol which isused in making the resins with which the present invention is concernedis on the order of 1:2.

3. The third group of amino nitrogen containcohol, preferably thelatter. To the alcohol solution is added aqueous formaldehyde, asecondary amine and suificient alcohol torkeep the concentration atabout the original figure. The mixtureis allowed to stand or maybeheated gently'until it becomes soluble in acetic acid, 6-18 hours,depending on temperature, usually being required. The final product, inorder to be acid soluble, should have at least 8-10%basic aminonitrogen. The maximum obtainable is around 22% and the products havingthe high percentages are the most desirable for use in the presentinvention. Examples I to Hi are directed to the use of a de-acetylatedchitin as an anchoring agent for the moistureproofing coating. Chitin isan acetylated carbohydrate aminepolymer, and may be, for convenience,termed chitose amine polymer, and after, the removal of the acetate, asby saponification, the product, which is believed to be a carbohydrateamine polymer, is capable of re-- acting with acids to form salts. Thede-acetylated chitin referred to in the examples given above, may beprepared as described in the Rigby U. S. Pat. No. 2,040,879, issued May19, 1936, one method or preparation being described as follows:

Example A Shrimp, lobster or crab shells are treated first with a 1%solution of soda ash at boiling temperature for about six hours, afterwhich the liquor is drained at! and the shells washed with water untilfree of alkali as tested byphenolphthalein. The washed shells are thensubjected fer a period of time to treatment with a 5% hydrochloric acidsolution until all lime salts have been removed (10 to 12 hours atordinary temperatures). After washing with water to remove the acid, theshells are given a second treatment with a soda ash solution containingabout 0.02% ordinary soap, the treatment being carried out at-theboiling temperature of the solution for a period of about 8 hours.After-this treatment the shells are drained free of the liquor andwater-washed until free of alkali as tested by phenolphthalein,whereupon they are centrifuged to remove as much water as possible. Theshells are then treated with 40% sodium hydroxide at ,110 degreescentigrade for about four hours, after after drying at 65 degreescentigrade, may be used to prepare solutions in acids as desired.

The chitin may be partially or completely deacetylated depending on theconditions present during the de-acetylation. Themore complete thede-acetylation, the more soluble is the salt produced by reacting withacid.- Thus chitose amine polymer, from which the acetyl substituentsome degradation of this chitose amine polymer takes place and theextent of degradation increases as the de-acetylation becomes morecomplete. must be a balance established between the completenessofde-acetylation and the degradation of the de-acetylated product. Forordinary purposes, it will be sufiicient to use a'product prepared fromchitin which has been 85 to 90 per cent de-acetylated. It will beunderstood that this range of de-acetylation is not limitative sincechitin, which has been de-acetylated to an extent as low as 50 per centor lower or as high as 100 per cent, may be used with advantage.

It has been stated that chitin is believed to be an acetylatedcarbohydrate amine polymer. This is in accordance with the evidencepresent ed in the literature. It is alsobelieved to be an acetylatedmixed or cross or inter-polymer of two carbohydrate amines. We do notwish, however, to be limited to theory, but cover the use of thede-acetylated chitin regardless of its ultimate molecular composition.

While the de-acetylated chitin is the preferred form of anchoring agentfor the coating which is used for the cellulose film, the invention alsocontemplates the use of other carbohydrate amine polymers such aschondrosin which may be obtained by the de-acetylation' of chondroitin-(believed to be an acetylated carbohydrate (chondrose) amine polymerand which is obt'ainable from animal cartilage in a manner a madesoluble by causing it to react with any one of a larger number of acidsincluding acetic, formic,

' citric, glycolic, malic, maleic, succinic, adipic,

phtha-lic, tartaric, benzoic and hydrochloric acids, and the, like.Coatings or films prepared from aqueous solutions of these water-solublesalts, upon beingdried, preferably at an elevated temperature, are moreor less rapidly rendered insoluble both in water and in organicsolvents.

In the case of salts formed by reacting with volatile acids,particularly volatile acids which are only slightly ionized, like aceticacid, the conversion to insolubility is easily and quickly accomplishedsince the acid, being weak or slightly ionized is readily dissociatedfrom its salt and being volatile is easily removed by heat, leaving. aninsoluble residue. Salts formed from the nn-volatile acids and/or fromthe highly ionized acids are much less readily converted toinsolubility, and consequently in the practice of this invention, it ispreferred to use salts of the de-acetylated chitin and of volatile acidsof Thus, for purposes .of expediency, there.

acids, these salts may be convertedinto the insoluble form by treatmentwith ammonia, as, for

example, in the form of gaseous ammonia (see,

Example II).

Any suitable concentration of de-acetylated chitin may be employed inthe aqueous solution of its salt, depending upon the method of operationused and the amount of size which it is desired to have present inthe'finish'ed cellulosic sheet. In general, it is preferred to usesolutions in which the concentration of the de-acetylated chitin salt isequivalent to between 0.2 and 2.0 per cent by weight. As .has beenstated, however, higher or lower concentrations may be desirable attimes for different eflects or'with different methods of applying thesize. The amount of size present in the finished celulosic sheet iscontrolled by the concentration of deacetylated chitin salt in thesolution and by the amount of this solution removed from the wet sheetby squeeze rolls or by other means, prior to the drying of the sheet. Inthe preferred form of this invention, this amount ranges from 0.5 to 4.0per cent of the weight of the sheet, although it may at times bedesirable for certain purposes to have present in the sheet an amount ofsize greater or less than those included within these limits.

The preparation of various amino polymers is fully discussed in Rigby U.S. Patent No. 2,040,- 879, issued May 19, 1936, relating to thepreparation oi de-acetylated chitin; .and in a number of copendingapplications such as for instance, Graves Serial No. 21,807, filed May16, 1935 relating to polymeric amino alcohol esters of alpha substitutedacrylic acid; Harmon Serial No. 21,- 810, filed May 16, 1935, relatingto polymeric salts of amino alcoholic esters of alpha substitutedacrylic acid; Meigs Serial'No. 59,643, filed January 17, 1936, relatingto amino proteins; Hardy Serial No. 61,842, filed January 31, 1936,relating to amino celluloses soluble in dilute acetic acid; HaskinsSerial No. 61,806, filed January 31, 1936, relating to alkylaminocelluloses soluble in at least a stoichiometrical amount of 5% aqueousacetic acid; Baithis Serial No. 69,725, filed Mar. 19, 1936, relating tothe resin prepared by reacting vinyl ketone polymers such as methylvinyl ketones with ammonia or a primary amine; Greenewalt Serial No.69,723, filed Mar. 19, 1936, relating to hydrogenating ketone resins inthe presence of ammonia or a primary or secondary amine; and Harmon &Meigs Serial No. 85,820, filed June 17, 1936, relating to thepreparation of amine-phenol-aldehyde resins.

To further illustrate the preparation of a few of'thes'e amino polymersthe following examples are given.

Example B distilled until all the moisture present in the reagent hasbeen removed. Beta-diethylaminoethyl methacrylate is isolated bycollecting the fraction boiling at 85:5 0. at 5 mm. pressure,

carefully washing 8 times with cold water to remove traces ofp-phenylene diamine, drying with anhydrous magnesium sulfate, filtering,washing the drying agent with ether, combining the washings wi h thebulk of the product and then distilling the ether under reduced pressurein an atmosphere of nitrogen. The monomeric ester is left in thedistilling glass as an almost colorless liquid which polymerizesspontaneously to a tough, transparent, pale amber polymer. When allowedto stand at room temperature or even at a lower temperature, the polymerwas insoluble in water and in the common oxygenated organic I solvents,soluble in acetone.

Example C To a solution of 220 ccs. of formalin (37% aqueousformaldehyde) containing 1 gram of potassium carbonate, there is added250 ccs. piperidene while the mixture is cooled with tap water. Thismethylolpiperidene solution is then added to a mixture of 1,500 ccs. ofmethanol, 75 cos. of water, and 250 grams of zein. The solution is mixedthoroughly with mechanical agitation and allowed to stand over night. Itis centrifuged to remove insoluble materials and then concentrated invacuo: The concentrated Fifty grams of polymeric methyl vinyl ketone aredissolved in 250 grams of dioxan and agitated overnight with grams ofcyclohexylamine. A test showed that the resin was not readily soluble indilute acids; hence, the reaction mixture is heated in a steam bath for5 hours. The resin is then precipitated. By pouring the reaction mixturein water and after standing 12 hours in fresh I phenol.

water, it is filtered and dried in vacuo, The yield is 55 grams. Thepulverized resin is soluble to the extent of 4 grams in 96 gramsof 5%aqueous solution of acetic acid.

Egcample' E 1 A solution of -18 grams (0.4 mol.) of dimethylamine in32.4 grams (0.4 mol.) of 37% aqueous formaldehyde was added withmechanical stirring and cooling to 53.5 grams (0.5 mol.) of 88% To theabove mixture, a solution of 81 grams (1 mol.) of 37% aqueousformaldehyde and 30.4 grams (0.5 mol.) of 28% aqueous ammonia was addedwith cooling. The resulting solution was gradually heated in a waterbath to 90 C. and held at that temperature for 5 hours. The resultingresin was purified by grinding it to a uniform slurry in the presence ofa little water in an ice cold mortar, followed by filtration and washingwith ice cold water. After drying, it weighed 74 grams. It was a yellowmaterial which softened slightly above room temperature. It was solublein acetone, ethyl acetate, dioxan, 10% aqueous sodium hydroxide, 1.5%aqueous acetic acid, 3%- formic acid, and 90% toluene-10%ethanolmixture.

There are of course numerous other amino polymers that can be preparedin much the same way as will be apparent from a study ofthe'applications specifically referred toabove,suchasfor instancebeta-dimethylaminomethyl methacrylate; beta-dicyclohexylaminoethylmethacrylate;

beta-di-N-butylaminoethyl methacrylate; betamorphollne-N-ethylmethacrylate; triethanolamine monomethacrylate; dimethylaminomethyl vaniline; and many others.

- Instead of simple polymers, interpolymers may be prepared, forinstance by reacting methyl methacrylate and methyl vinyl ketone in thepresence of ammonium hydroxide or reacting beta-cyclohexylamino'ethylmethacrylate monomer and beta-dimethylaminoethyl methacrylate monomertogether under suitable conditions. Other equivalent polymeric materialssuch as c0- polymers may also be used, provided their solubilitycharacteristics are as previously set forth. In order that the finishedcellulosic sheet may be of the desired degree of softness, a softeningagent, such as glycerin, is incorporated in the aqueous solution of thesize. The aqueous solution may be applied to the cellulosic sheet byimmersing the sheet in the solution or by brushing or spraying thesolution onto the sheet, or by applying the solution to the sheet byrollers or by any other convenient means. Moreover, the size solutionmay be applied either to the cellulosic sheet in the gel condition ortothe finished dry cellulosic sheet by another operation. We prefer,however, to apply it to the gel sheet from the glycerin bath. In thestep of drying the cellulosic sheet treated with a solution of the size,for example, the acetate of de-acetylated-chitin, in which step thesoluble salt is converted to an insoluble coating or sizing on thesheet, a wide range of temperature is possible. We prefer,

however, to carry out the drying operation at temperatures between 50degrees and 90 degrees centigrade. In certain cases, as has been statedin the preceding paragraph, vapors of basic compounds, such as ammonia,may be losic sheet, which has been dried or partiallydried after theapplication of the solution of the size, with a solution of a basiccompound, such as dilute ammonium hydroxide, a solution of ethylenediamine, or of triethanolamine or the like.

As has been stated, the greatest advantages follow from the useofde-acetylated chitin as an anchoring agent for moistureproofingcoatings applied to regenerated cellulose or to other cellulosic filmsof the character described. It will be understood that it can in generalbe used to anchor coatings for transparent cellulosic sheeting wheresuch coatings have less or greater moistureproofing properties thanthose described in the examples given above.

, periods. of time.

The present invention effects the production of flexible, substantiallyodorless, non-fibrous, nonporous cellulosic sheets or films having amoistureproofing coating securely anchored to the film base andresistant to deterioration when subjected to the action of liquid waterover long Further advantages are the adaptability of the process of theinvention to equipmentnow used for the production of regeneratedcellulose film and the like, without necessitating a substantial changein the design of such equipment; lower cost, minimum waste and greatefficiency. Where no pigment is used, the composite films have a highdegree of transparency.

The term "de-acetylated chitin, as used in the claims, is intended toinclude the product which is prepared by removing the acetyl groups fromchitin in any suitable way. Unless otherwise qualified, the term alsoincludes the product we pared by solubilizing the de-acetylated chitin,as, for example, by forming a salt with an acid, and

by .again'insolubilizing. It is also intended to include any otherproduct substantially identical therewith; as, for example, where suchproduct is produced synthetically.

In some instances the dried cellulosic sheet coated or sized withde-acetylated chitin may retain a very faint trace of the characteristicodor of the acid used in forming the water-soluble salt. This trace ofodor may readily be removed by treating the sheet with dilute vapors ora dilute solution of a basic compound like ammonia to neutralize theacid, by volatilizing the acid by means of heat, or by a current of airor steam, or by any known deodorlzing treatment. If desired, the aqueoussolution of the size may be subjected to treatment with activated carbonin order to remove any undesirable odor.

While the invention has been described particularly with respect totransparent wrapping tissues, itwill be understood that within its broadscope, the invention includes the anchoring of coatings to sheets whichare thicker than wrapping tissues. The invention is also applicable tothe anchoring of coatings to tubes, sausage casings, bottle caps andbands, molded articles, and, in general, to any articles of cellulose orsimilar material of the character described, where the problem ofanchoring coatings arises.

The preferred form of the invention resides in the anchoring ofmoistureproofing surface coatings to a non-porous, non-fibrous base suchas regenerated I cellulose. scope, the invention comprehends also thecoating of other bases, e. g., rayon fabric and the like,

in order" to anchor surface coatings thereto. Even where the coating ofthe base, whether it be non-porous or of other character, isdiscontinuous in character, such, for example, as in the printing ofcolors, symbols, indicia, advertisements, etc., the de-acetylated chitinmay be used as the anchoring agent. Thus, regenerated cellulose sheets,tubes, caps, sausage casing, etc., when coated or sized withde-acetylated chitin may be printed with printing ink either having alacquer base-or a drying-oil base, to give any desired indicia, and,after drying, the printing re mains securely anchored to the base evenafter being subjected to rigid washing, boiling or other processingsteps.

Additionally, the present invention may be used to improve the anchorageof various coatings to bases other than those specifically noted above,for example, paper, cotton cloth, and

Within its broadest other bases which are water sensitive, i. e., willabsorb water, the anchoring agents improving the adhesion between thecoating and base over that exhibited where the coating is applied to thebasein the absence of the anchoring agent.

The invention also contemplates the production of coated self-sustainingfilms of de-acetylated chitin formed by casting or otherwise forming thede-acetylated chitin into the desired form and then applying a coating.

For the purposes of this invention, moistureproof materials are definedas those which, in the form of a thin,,continuous and unbroken film,will permit the passage of not more than 690 grams of water vapor per100 square meters per hour, over a period of 24 hours at approximately395 C.:0.5 C., the relative humidity of the atmosphere at one side ofthe film being maintained at least at 98% and the relative humidityoi'the atmosphere at the other side being maintained at such value as togive a humidity differential of regenerated cellulose of thicknessapproximately 0.0009", will produce a coated product which ismoistureproof.

A moistureproofed regenerated cellulose sheet is capable of resistingthe passage of moisture or water vapor at least ten times as effectivelyas the uncoated regenerated cellulose sheet.

Parts, proportions and/or percentages referred to throughout thespecification and claims are to be construed as parts, proportionsand/or percentages by weight unless indicated otherwise.

Any variation of or modification of the invention, as it has beendescribed above in this application, which conforms to the spirit of theinven tion, is intended to be included within the scope of the claims.

We claim: I

1. An article of manufacture comprising a watersensitive base, a surfacecoating and an intermediate coating comprising an amino polymer which issubstantially insoluble in water and in 5% aqueous ammonia but solublein 2% aqueous acetic acid.

2. An article of manufacture comprising a water-sensitive non-fibrousbase, a surface coating and an intermediate coating comprising an aminopolymer which is substantially insoluble in water and in 5% aqueousammonia but soluble in 2% aqueous acetic acid.

3. A composite film suitable for use as a wrapping tissue comprising awater -sensitive, nonfibrous base, a surface coating and an intermediatecoating comprising an amino polymer which is substantially insoluble inwater and in 5% aqueous ammonia but soluble in 2% aqueous acetic acid.

4. A composite film suitable for use as a wrapping tissue comprising awater-sensitive, nonfibrous base, a moistureproofing coating and anintermediate coating comprising an amino polymer which is substantiallyinsoluble in water and in 5% aqueous ammonia but soluble in 2% aqueousacetic acid.

5. In a process for producing an article comprising a water-sensitivebase and a surface coating which adheres tenaciously to the'base evenwhen in contact with water over long periods of time, the steps whichcomprise applying to the assigns base an intermediate coating comprisingan a de-acetylatedchitin, and; a surface coating amino polymer, which issubstantially insoluble in water and in aqueous ainmonia but soluble in2% aqueous acetic acid, then applying a surface coating;

6. In a process for producing an article comprising a water-sensitive,non-fibrous base and a surface coating which adheres tenaciously to thebase even when in contactwith water over long periods of time, the stepswhich comprise applying to the base an'intermediate coating comprisingan amino polymer which substantially insoluble in water and in5% aqueousammonia but soluble in 2% aqueous acetic acid, then applying a surfacecoating.

7. A composite film suitable for use as a wrapping tissue comprising anon-fibrous cellulesic sheet; an intermediate coating comprising asieacetylated chitin, and a surface coating said sheet and said surfacevcoating exhibiting an adhesion greatly improved over that exhibitedbetween a similar sheet and surface coating when in direct contact witheach other, said adhesion being tenacious even when the composite filmis subjected to contact with Water over a long period of time.

8. A composite film suitable for use as a wrapping tissue comprising asheet of regenerated cellulose, an intermediate coating comp-rising adeacetylated chitin, and a surface coating.

9. A composite film suitable for use as a wrapping tissue comprising asheet of regenerated cellulose, an intermediate coating comprising adeacetylated chitin; and a surface coating comprising a meistureproofingcomposition.

19. A composite film suitable for use as a wrapping tissue comprising anon-fibrous cellwosic sheet, an intermediate coating of a de-acetylatedchitin, and a surface coating which contains a cellulose derivativebase, said sheet and said surface coa ting exhibiting an adhesiongreatlyimproved over that exhibited between a similar sheet and surfacecoating when in direct contact with each @other, said adhesion beingtenacious even when @the composite film is subjected tocontact withwater over a long period of time.

able for use as a wrapping tissue, the steps comprising applying anaqueous solution of a'solubilized de-acetylated chitin to a sheet ofregenerated cellulose, (trying the treated sheet. and then applying amoistureproofing surface coating. 7

12. A composite film suitable for use as awrapping tissue comprising asheet of regenerated celluiose, an intermediate coating of a member ofthe class consisting of de-acetylated chitin and de-acetylatedchondroitinand a surface coating.

13. A printed article comprising a water sensitive base having printingthereon and provided with an anchoring agent for the printing comprisinga de-acetyiated chitin.

14. A nioistureproof composite film suitable for i use as a wrappingtissue comprising a sheet of regenerated cellulose, an intermediatecoating of 11. In a process for preparing a product suit V a surfacecoating.

' of a de-acetylated chitin and an acid.

comprising a moist'nreproofing cellulose deriva-' a baseand surfacecoating which exhibit a greatly improved adhesion of such a character asto remain tenacious when subjected to contact with water over longperiods of time, the steps which comprise applying a coating comprisinga solution of de-acetylated chitinio a non-fibrous, cellulosic'sheet,drying the sheet, and then applying 16; The process of claim 15characterized in thatthe solution is an aqueous solution of a salt 1'7.The process of claim 15 characterizedin that the solution is an aqueoussolution of a salt of a de-acetylated chitin and an acid, said solutionalso containing a softener for the cellulosic sheet. r

-18. The process of claim 15 characterizedin that the solution is anaqueous solution of a salt oga de-acetylated chitin and an acid, andfurther characterized in that the sheet is treated with a basic materialprior to applying the surfacecoating.

,19. The.process of claim 15 characterized in that the solution is anaqueous solution of a salt of a de-acetylated chitin and an acid, andfurther characterized in that the sheet is treated with gaseous ammoniaduring drying.

20. A composite article comprising a watersensitive base, anintermediate coating of the ciass consisting of de-acetylated chitin anddeacetylated chondroitin, and a surface coating, said base and saidsurface coating exhibiting an adhesion *greatly improved over that.exhibited between a similar base and surface coating when in directcontact with each other; said adhesion being tenacious even when thecomposite film is subjected to contact with water over long periods oftime;

2 21. The process which comprises applying a fluid coating compositionto de-aeetylated chitin, converting the coating composition into a solidcoating, whereby to obtain a composite article in which the coatingadheres to the de-acetylated chitin tenaciously even when the compositearticle is subjected to the action of water for a long period of time.

: 22. A composite article comprising a watercontact with each other.-

ERNEST K. GLABDING. DOROTHY BATEMAN MANEY.

